Magnetostrictive / piezo remote power generation, battery and method

ABSTRACT

A power generation device generates power by subjecting a composite of magnetostrictive material and piezo material to a magnetic field. The composite of magnetostrictive material and piezo material may be incorporated in a battery or other storage device.

CROSS REFERENCE TO RELATED APPLICATION

The present application is based upon and claims the benefit of U.S.Provisional Application Nos. 60/816,010 filed Jun. 22, 2006, and60/831,619 filed Jul. 18, 2006.

BACKGROUND OF THE INVENTION

In the manufacture and use of RFID (Radio Frequency Identification) thetechnology is divided into two major groups; Passive Tags that gathertheir power from close coupling to a reader thus enabling them totransmit or reflect information back to the reader. The second group isActive Tags which have their own power storage capability like abattery, capacitor or other devices. The tag is queried with a RF signalgenerated by the reader requesting the tag to transmit the data, whichis received by the reader. This Active tag has a limited life due to thestorage device's limited shelf life. The magnetostrictive/piezo deviceof the present invention provides power to operate an attachedelectrical device or to charge an electrical storage device that couldbe used by a multitude of sensors, receivers, transmitter or otherelectrical or electronic device. The new type of RFID using this powergenerating technology is hereinafter referred to as Network Powered Tagor NPRFID.

SUMMARY OF THE INVENTION

The present invention relates to a power generating device which iscontrolled from a natural or man-made pulsed or constant remotelyoperated magnetic or electromagnetic field, to a battery charged therebyand to a method for forming said battery. Magnetically affecting themagnetostrictive or similar material, causes a stretching, bending ordisplacement of a power producing crystal or material such as piezowhich produces power each time a pulse of magnetism is sensed. The newpower generating device produces power from a PME (PassiveMagnetostrictive Electro-Active) device or similar devices. A passivemagnetic field sensor made of layers of Terfenol-D {Fe2(Dy0.7Tb0.3)}magnetostrictive material and ceramic PZT-5 will act as a generator topower electrical and electronic devices when in range of the queryingtransceiver magnetic field of (0.3 Oersted or larger). Themagnetostrictive material or other material stretches, flexes or isphysically distorted when in the presence of a magnetic field or pulsedmagnetic field displaces the piezo type device attached thereto thereby,generating power for any electric or electronic device.

Under a preferred embodiment, when the power is generated, it will bestored in a bank of ferroelectric capacitors, capacitors or arechargeable battery type device. The battery could be a rolled-up sheetof up to a few thousand of ferroelectric capacitors, all hooked togetherin parallel. Building ferroelectric capacitors larger than a certainsize has not heretofore been successful. Therefore, in order to create alarge ferroelectric capacitor, large numbers of smaller capacitors arebuilt and wired in parallel to equal one large capacitor. The process issimilar to the manufacture of integrated circuits where layers ofmaterial are deposited on top of other material and then etch away thatmaterial that is not needed. By doing this, it is possible to make largecapacitors on a sheet of polyester such as Mylar® or polyimide such asKapton® which is then rolled up to make a package that can fit easilyinto a cylinder as used in normal battery packaging.

The PME power generator/battery will generate power with each pulse of amagnetic or electromagnetic field. Pulsing of the magnetic source willallow the device to charge up a battery or capacitor to a usable levelof voltage or current. In order to obtain optimum power, the magneticfield should be generated at a frequency that matches the naturalfrequency of the magnetostrictive/piezo composite. Power close tooptimum power can be obtained if the magnetic field is generated at afrequency in the range of 90% to 110% of the natural resonant frequencyof such composite. Additionally, the new magnetostrictive/piezo deviceproviding power to a battery, capacitor or other storage device could beused in conjunction with a voltage regulator to provide a specificelectrical voltage. The device could also function without the use of aregulator in some applications. This power generated would be encased ina typical or non-typical battery enclosure that could be used by alldevices that utilize AAA, AA, C, D or other common battery forms. Thisnew power generating battery would be called a NPB (Network PoweredBattery). The battery could be powered by single or multiple magneticgenerating devices. Additionally, a single magnetic generating devicecould power multiple NPBs. This new device could be configured to supplypower to any number of battery powered devices and could also power andquery a RFID tag at long distances.

The magnetic pulsed field could also be coded to provide instructions tothe receiving device to turn-on, turn-off, or other specific task oroperation such as store new data in memory, erase memory or go to sleep.

One preferred embodiment of the present invention can increase thecapability over current battery technology by maintaining an ongoingcharge to power the utilizing equipment, thereby providing a potentiallyinfinite shelf life. This will have significant advantages inreliability of the utilizing equipment. The present invention could alsoprovide a power source for medical, biomedical, night vision, GPS,radios, sensors, actuators and intelligence gathering technologies. Theability to transmit data to the battery can provide additional benefitssuch as power conservation, mode changes, data refresh and others.

Magnetostrictive Materials were discovered in the 1840s by JamesPrescott Joule, when he noticed that iron changed length in response tochanges in magnetism and named the phenomenon the Joule Effect.

How It Works:

Magnetostrictive materials expand when exposed to a magnetic field,exhibiting the Joule Effect or Magnetostriction. This occurs becausemagnetic domains in the material align with the magnetic field.Similarly, when the material is strained (stretched or compressed), itsmagnetic energy changes. This phenomenon is called magnetomechanicaleffect or Villari Effect.

Some examples of magnetostrictive materials:

-   -   cobalt    -   iron    -   nickel    -   ferrite    -   terbium Alloys (Terfenol-D)    -   Metglass    -   Galfenol (Gallium and Iron)

Since magnetostriction involves a bidirectional energy exchange betweenmagnetic and elastic states, magnetostrictive materials when puttogether with a piezo material, provide a mechanism to produce an ACvoltage from an alternating electromagnetic field.

IN THE DRAWINGS

FIG. 1 is a schematic view showing the basic concept of magnetostrictiveexpansion.

FIG. 2 is a perspective view of joined materials forming a composite ofthe present invention.

FIG. 3 is a schematic view showing the mechanism of magnetostriction.

FIG. 4 is a wiring diagram showing prior art use of a coil forgenerating power.

FIG. 5 is a wiring diagram showing generation of power by themagnetostricitve-piezo composite.

FIG. 6 is a diagram of a circuit that creates the electromagnetic fieldthat can be modulated with commands and data.

FIG. 7 is a sectional view of one form of battery according to thepresent invention.

FIGS. 8 a and 8 b are views of another embodiment of battery (FIG. 8 a)and an array of such batteries mounted on a substrate (FIG. 8 b).

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates the Joule magnetostriction ΔL/L of a cylindricalsample 10, resulting from a magnetic field (H) being applied along thelongitudinal axis X. The cylindrical sample 10 of magnetostrictivematerial is caused to stretch from a length L prior to application of amagnetic field to a length L+ΔL during application of a magnetic field.

FIG. 2 illustrates a layer of magnetostrictive material 12 and a layerof piezoelectric material 14 bonded together forming a composite 20 ofthe magnetostrictive material and the piezo material. The composite,which could have a variety of configurations, is placed in a magneticfield H. When the magnetic field H is applied to the composite 20, themagnetostrictive material 12 stretches and thereby places a strain onthe piezoelectric material 14 thus inducing a proportional voltage inthe piezoelectric material 14. Depending on the configuration of thecomposite 20, the application of the magnetic field could cause themagnetostrictive material 12 to stretch, bend or be otherwise distorted.

Information regarding magnetoelectric laminate composites andmagnetostrictive alloys may be found in Applied Physics Letter No.87-222504 dated 28 Nov. 2005 which is incorporated herein by reference.

Referring to FIG. 3, there is shown schematically a representationcomparing (1) in the upper portion of FIG. 3, molecules M of themagnetostrictive material 12 positioned randomly when not subjected to amagnetic field H and (2), in the lower portion of FIG. 3, alignment ofthe molecules M when the magnetostrictive material 12 is subjected to amagnetic field H. As can be seen in FIG. 3, the length of themagnetostrictive material 12 increases as the molecules M align with theapplication of the magnetic field (H). The increase in length isdesignated by the letter e.

The mechanism of magnetostriction at an atomic level is relativelycomplex subject matter but on a macroscopic level may be segregated intotwo distinct processes. The first process is dominated by the migrationof domain walls within the material in response to external magneticfields. Second, is the rotation of the domains. These two mechanismsallow the material to change the domain orientation which in turn causesa dimensional change. Since the deformation is isochoric, there is anopposite dimensional change in the orthogonal direction. Although theremay be many mechanisms to the reorientation of the domains, the basicidea, represented in FIG. 3, remains that the rotation and movement ofmagnetic domains causes a physical length change in the material.

FIG. 4 is a wiring diagram showing the prior art use of a coil 16 forgenerating electricity. A typical prior art RFID device uses acoil-capacitor 16 to capture the electromagnetic field to power up theRFID device. This technique works well for ranges up to a meter. Theelectromagnetic field (H field) drops off at an exponential rate as thedistance between the RFID device and the power source increases. Thus,the sensitivity of the coil-capacitor 16 cannot capture enough energyfrom a power source location beyond about one meter from the prior artRFID device and its coil capacitor 16.

FIG. 5 is a wiring diagram showing short-medium-long range powering by amagnetostrictive-piezo composite 20 as set forth in the presentinvention.

The present invention takes advantage of a highly efficient mechanismthat creates electrical energy from a weak magnetic field. Due to thefact that the composite 20 is much more efficient than a coil capacitor,the composite 20 will operate at a much lower magnetic field thereby alonger range. Also, as the device that contains composite 20 is movedthrough the earth's magnetic field, a voltage will be generated. Thiswill allow device to be recharged by simply moving it.

A magnetostrictive-piezo device utilizing the composite 20 in a size ofapproximately one cm square can produce one volt per Oersted of magneticfield strength. (The earth's magnetic field is approximately one halfOersted.)

Referring to FIG. 6 there is shown a circuit that creates theelectromagnetic field that can be modulated with commands and data. Anoscillator 101 runs at a frequency 4.00 MHz. The oscillator 101 can alsobe the oscillator for the microprocessor (not shown). In mostmicroprocessor designs, a crystal is used to clock the microprocessor.The crystal used for the microprocessor can be shared for the coil drive105 hereinafter described. The output of the oscillator 101 drives acounter/divider 102 that receives the 4.00 MHz signal and divides it by32. The counter/divider 102 creates a 125 kHz square wave signal. If themicroprocessor crystal was 8 MHz, it would be necessary to divide thefrequency by 64 in order to obtain the required 125 kHz signal. A nandgate 103 is provided that can turn on and off the 125 kHz signaldepending on the level of the data input. If the data input is a one,the 125 kHz will pass through. If the data input is a zero, the 125 kHzsignal will be blocked and no signal will pass through to the inverter104. The inverter 104 creates two phases of the 125 kHz signal to drivea coil-capacitor 106 from both ends. Two drives 105 that are heavycurrent devices are provided. They can drive the coil-capacitor 106 fromboth ends. By driving the coil-capacitor 106 this way with the heavycurrent drivers 105, less voltage is required from the power supply. Ifthe coil were driven from a single side, the result would be one-half ofwhat can be obtained by driving the coil-capacitor 106 on both sides.The end result is an electromagnetic field emanating from thecoil-capacitor 106 and radiating into the area around the coil capacitor106.

Referring to FIG. 7, there is shown a battery 30 formed according to thepresent invention. Although the battery 30 shown in FIG. 7 has anexterior shape of a typical flashlight, penlight, battery, for example,with a size of A, AA, AAA, C or D, such battery 30 could have a widevariety of shapes and constructions. All battery types could be acandidate for replacement with this type of device.

As shown in FIG. 7, there is provided a battery 30 or other storagedevice such as a ferro-capacitor device having a substantiallycylindrical casing 32 with a positive terminal 34 at one end and anegative terminal 36 at the other end. A voltage regulator 38 is shownpositioned slightly below the midpoint of the casing 32. The voltageregulator 38 could be one such as that sold by National Semiconductor,San Jose, Calif., as its item No. LM78L05. The upper area 39 between thevoltage regulator 38 and the positive terminal 34 has positioned thereina capacitor or a ferro capacitor. Capacitors and ferro capacitors arewell known in the art of integrated circuits. Between the voltageregulator 38 and the negative terminal 36 are one or moremagnetostrictive/piezo cells 20. If desired, the magnetostrictive/piezocell composite could be positioned between the voltage regulator 38 andthe positive terminal 34 and the PZT positioned between the voltageregulator 38 and the negative terminal. Additionally, for someapplications where regulation of voltage is not a factor, the voltageregulator could be omitted.

Referring to FIGS. 8 a and 8 b there is shown a modified embodiment ofbattery/capacitor 50 which is flat and could be quite small, forexample, if rectangular in shape, as small as 100 millimeters long and10 millimeters wide with a thickness in the range of ½ to 1 millimeters.A single modified battery/capacitor 50 is shown in FIG. 8 a and includesa substrate of thin flexible plastic such as Mylar® or Kapton®, a firstelectrode 52, a second electrode 54 and a discrete unit of PZT 58. Thefirst electrode 52 is mounted directly on the substrate 51. The discreetunit of PZT 58 is also positioned directly on the substrate 51 with thesecond electrode 54 being positioned on the discreet unit of PZT 58. Amagnetostrictive/piezo cell 56 is spaced from the battery/capacitor 50and is connected thereto through a voltage regulator 53 via wires 55 and57.

Referring to FIG. 8 b, there is shown a multitude of modifiedbatteries/capacitors 50 mounted on a flat sheet or substrate 60 ofMylar® ( or Kapton®. Although FIG. 8 b shows 48 batteries/capacitors 50mounted on the substrate 60, there could be hundreds or even more than athousand batteries/capacitors 50 mounted on the substrate 60. Thebatteries/capacitors 50 could have a voltage on the order of 1.5 voltsand generate amperage of 1 milliamp each. Thus, assuming 100batteries/capacitors 50 were mounted on the substrate 60 and wired inparallel, they could generate a current as high as 2 amps. A singlemagnetostrictive/piezo cell 56 can power many batteries/capacitors 50,possible as many as 10,000.

The substrate 60 of Mylar® or Kapton® should be thin enough so that thesubstrate 60 with the batteries 50 mounted thereon could be rolled intoa cylindrical form for convenience of usage. A thickness of 0.5 to 1millimeters for the substrate 60 would be suitable.

One type of passive magnetic magnetostrictive electroactive device is avibration energy harvester sold by Ferro Solutions, Inc., Cambridge,Mass. which is believed to incorporate features described in U.S. Pat.No. 6,984,902. Other prior art includes U.S. Pat. No. 6,725,713 whichdiscloses the use of piezoelectric materials for generating power from arotating tire.

Features of the magnetostrictive/piezo device and its use include:

-   -   The device generates electrical power with the use of magnetic        fields    -   The device uses magnetic or electromagnetic pulses to generate a        pulse of electrical power. The magnetic source can be from a        local or distant source.    -   Electrical power can be generated from the device by rotating        the device in a magnetic field or within the earth's magnetic        field.

Power can also be generated by transmitting an electromagnetic field tothe device at most frequencies but is most efficient at the resonantfrequency of the device.

-   -   The electrical power voltage and current is proportional to the        piezo or similar material.    -   When the piezo is flexed, distorted or displaced by any        material, specifically a magnetostrictive material, the piezo        material will produce a voltage.    -   The device's power can be used as a one time pulse or        accumulated in a battery or capacitor to attain larger voltages        or current.    -   The device could be utilized to power medical devices, sensors,        transmitters and other small devices that require minimal or no        maintenance or battery replacement.    -   The device can be used to power RFID devices using remote        magnetic field generation equipment.    -   Data can be transmitted on the pulsed power sources carrier        signal to the device to interrogate or direct the device to a        response. This information could be EPC, SKU or other serial        data.    -   The device generates electrical power with the use of magnetic        fields and stores the power in a bank of ferroelectric        capacitors or a rechargeable battery.

Electrical power can be generated from the device by rotating the devicein a magnetic field or within the earth's magnetic field. Power can alsobe generated by transmitting an electromagnetic field to the device atmost frequencies but is most efficient at the resonant frequency of thecomposite 20. A magnetic field outside such resonant frequency willactivate the magnetostrictive material but not as efficiently as if itwere at the natural resonant frequency of the composite or in the rangeof 90% to 110% of such resonant frequency. Sending the magnetic field atthe resonant frequency of the composite will allow the transfer ofenergy at a factor of 10× or more as compared to a non-resonantfrequency.

-   -   The electrical power voltage and current is proportional to the        piezo or similar materials characteristics. As would be        expected, a larger piece of piezo material will produce more        energy than a smaller one.    -   When the piezo is flexed, distorted or displaced by any        material, specifically a magnetostrictive material, the piezo        material will produce a voltage.    -   The device's power can be accumulated in a battery or capacitor        to attain larger voltages or current.    -   The battery being charged could be a rolled up sheet of up to        thousands of ferroelectric capacitor all hooked together in        parallel.

The above detailed description of the present invention is given forexplanatory purposes. It will be apparent to those skilled in the artthat numerous changes and modifications can be made without departingfrom the scope of the invention. Accordingly, the whole of the foregoingdescription is to be construed in an illustrative and not a limitativesense, the scope of the invention being defined solely by the appendedclaims.

1-23. (canceled)
 24. A battery comprising a structure having a firstterminal and a second terminal and formed by the process of: (a)positioning on said structure a composite of (i) a first material whichstretches, flexes or is otherwise displaced when subjected to a magneticfield and (ii) a material which generates electricity when subjected tostrain; (b) positioning a voltage regulator in said enclosure betweensaid composite and either said first terminal or said second terminal;and (c) positioning a capacitor or ferro capacitor on the opposite sideof said voltage regulator from said composite; and (d) subjecting saidcomposite to a magnetic field.
 25. The battery according to claim 24wherein the process of forming includes the step of subjecting saidcomposite to a pulsed or continuous magnetic field having a frequency inthe range of 90 to 110% of the natural resonant frequency of thecomposite.
 26. A battery according to claim 24 wherein said materialwhich generates electricity is lead zirconate titanate (PZT).
 27. Apower generation system comprising a composite of: (a) amagnetostrictive material which stretches, flexes or is otherwisedisplaced when subjected to a magnetic field, and (b) a second materialwhich generates electricity when subjected to strain, said secondmaterial being joined to said magnetostrictive material and placed instrain thereby upon stretching, flexing or other displacement of saidmagnetostrictive material.
 28. A power generation system according toclaim 27 wherein said second material is a compound of lead, zirconateand titanate (PZT).
 29. A combination of the power generation systemaccording to claim 27 and a coil driver system for creating anelectromagnetic field, said coil driver system including: an oscillatortransmitting a signal at a first frequency to a divider, said dividerreducing the frequency of said signal and transmitting said reducedfrequency signal to a nand gate, gated with data to toggle the signaloutput from an on to off position and from an off to on position, and aninverter for creating two phases of said reduced frequency signalreceived from said nand gate and transmitting said phases, respectively,to first and second drivers, said first driver transmitting said reducedfrequency signal to a first end of a coil-capacitor and said seconddriver transmitting said reduced frequency signal to a second end ofsaid coil-capacitor.